1. Field of the Invention
The present invention relates to a method for high frequency welding of non-polar thermoplastic elastomer compositions comprising a suitable modifier. Furthermore, the present invention relates to shaped articles obtainable by the method according to the present invention.
Conventional non-polar thermoplastic elastomer compositions comprising a thermoplastic polyolefin homopolymer or copolymer and an olefinic rubber which is fully crosslinked, partially crosslinked or not crosslinked and/or block-copolymer of styrene/conjugated diene/styrene and/or its hydrogenated derivative, optionally in the presence of common additives can only be adhered together by using adhesives or must be heat welded by the hot air or hot plate method. These conventional methods present several disadvantages such as, in the adhesive method, the need to modify the adhering surface, (for instance, by priming, corona treatment, etching, etc.), selection of the suitable adhesive, etc., and in the hot air and hot plate method, the relatively slow speed, the difficulty to control the temperature to obtain adequate welding without burning the surface.
High frequency welding is, however, not feasible with those thermoplastic elastomers. However, there is a need in the industry to make those thermoplastic elastomers accessible to the high frequency welding method.
The high frequency welding method is a well-known, well-established method of heat-sealing materials together, which method can easily be carried out. Said method is used in many sections of the industry such as inflatables (boats, containers, life-rafts, oil-booms, etc.), automotive, automotive ancillaries, office and school equipment, tenting, tarpaulins, packaging and for many other purposes, wherever proper adhesion is desired.
2. Description of the Related Art
U.S. Pat. No.4,728,566 pertains to a composite article comprising a polymer foam having HF-bonded thereto at least one surface layer, wherein the HF-bonding is effected by a layer of HF-bondable polymer film between said foam and said surface layer, said HF-bondable polymer film comprising a carbon monoxide-containing olefin interpolymer and said polymer foam being selected from the group consisting of various foamed polymers. The surface layer is selected from the group comprising polymers, fabrics, leather, cellulosic products, wood, vitreous materials, metal foils, paper and foams and the HF-bondable polymer film comprises at least one of ECO, ECOAA, ECOMAA and ECOVA.
U.S. Pat. No.2,667,437 discloses a method to heat-weld two non-polar, unmodified thermoplastics by exposing them to a pair of hot electrodes which are covered with a fixed conductive polymer.
U.S. Pat. No.4,268,388 pertains to almost the same welding-method as disclosed in U.S. Pat. No.2,667,437.
U.S. Pat. No.3,336,173 discloses the addition of a polyamide to non-polar thermoplastics in order to obtain a HF-weldable product without taking into consideration the very poor properties of such a blend due to the lack of compatibility between the non-polar thermoplastic and the polar polyamide.
EP-A-0,028,106 discloses the use of a special bituminous petroleum derivative as a HF-welding promotor in chlorinated PE/chlorosulfonated PE.
The available prior art does not suggest how non-polar thermoplastic elastomers could be welded by the high frequency welding method.